// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// A fuzzer that checks correctness of json parser/writer.
// The fuzzer input is passed through parsing twice,
// so that presumably valid json is parsed/written again.

#include <stddef.h>
#include <stdint.h>

#include <string>

#include "base/json/json_reader.h"
#include "base/json/json_writer.h"
#include "base/json/string_escape.h"
#include "base/logging.h"
#include "base/values.h"

// Entry point for libFuzzer.
// We will use the last byte of data as parsing options.
// The rest will be used as text input to the parser.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
{
    if (size < 2)
        return 0;

    int error_code, error_line, error_column;
    std::string error_message;

    const std::string input_string(reinterpret_cast<const char*>(data), size - 1);
    const int options = data[size - 1];
    auto parsed_value = base::JSONReader::ReadAndReturnError(
        input_string, options, &error_code, &error_message, &error_line,
        &error_column);
    if (!parsed_value)
        return 0;

    std::string parsed_output;
    bool b = base::JSONWriter::Write(*parsed_value, &parsed_output);
    LOG_ASSERT(b);

    auto double_parsed_value = base::JSONReader::ReadAndReturnError(
        parsed_output, options, &error_code, &error_message, &error_line,
        &error_column);
    LOG_ASSERT(double_parsed_value);
    std::string double_parsed_output;
    bool b2 = base::JSONWriter::Write(*double_parsed_value, &double_parsed_output);
    LOG_ASSERT(b2);

    LOG_ASSERT(parsed_output == double_parsed_output)
        << "Parser/Writer mismatch."
        << "\nInput=" << base::GetQuotedJSONString(parsed_output)
        << "\nOutput=" << base::GetQuotedJSONString(double_parsed_output);

    return 0;
}
